DESCRIPTION: Studies of treatment-associated morbidity are becoming increasingly important as clinical trials continue to document equivalent mortality rates for a variety of treatment options for breast cancer. Lymphedema has been identified by women who experience it as one of the most distressing long-term consequences of breast cancer treatment; yet there are insufficient data about its incidence and risk factors to counsel women appropriately. Sparse data suggest that risk may be higher in older women. The Specific Aims of the proposed study are: 1) to measure prospectively the incidence of lymphedema and identify risk factors for its occurrence, using multivariate modelling to estimate the relative risk of lymphedema associated with characteristics of the disease at diagnosis, and with treatment, recurrence and patient-specific factors; and 2) to measure health-related quality of life in breast cancer patients with and without lymphedema, taking into account age, stage of disease, cancer treatment, co-morbid conditions and other patient factors that can influence the quality of life. A combined cross-sectional and prospective cohort design will be used for this population-based study. A random sample of 900 patients newly diagnosed with primary breast cancer from Philadelphia and Delaware Counties of Pennsylvania will be used to estimate the prevalence of different treatment modalities for breast cancer and will be followed prospectively to assess the incidence of lymphedema and risk factors for its occurrence, as well as morbidity accompanying lymphedema, taking into account type and extent of disease at diagnosis and other potentially confounding factors. Data collection will include an in-person, hoe interview, seven months after diagnosis to measure pre-existing characteristics of patients that may be associated with late occurrences of lymphedema, and to assess the presence of lymphedema and arm-related morbidity; telephone follow-up interviews at 13, 19 and 25 months after diagnosis to measure the occurrence of lymphedema and arm-related morbidity, and exposures during the interval that may be associated with risk of lymphedema; in-person observation of all patients whose questionnaire results indicate the presence of lymphedema and a random sample of women, who do not report lymphedema, and medical records review to obtain clinical data regarding the characteristics of the disease at diagnosis, treatment modality, and recurrence.